Our principal aim is to purify inhibin which is a peptide hormone produced by the gonads. Once we have purified inhibin we shall determine its chemical structure using classical methods of peptide analysis and sequencing. To achieve this we have to discover better methods to improve our yields of inhibin from its starting material..ovine rete testis fluid. We have yet to examine two procedures which we believe will be helpful to achieve these goals. These are the use of antibodies to prepare an immunoaffinity column. At present we have antibodies which neutralize the biological effects of inhibin in vitro. The second method will be to use high performance liquid chromatography as an ultimate or penultimate to final purification step. We shall aslo develop a radioligand assay for inhibin which should be much more sensitive than our current in vitro bioassay for inhibin. We feel confident that with such an assay we shall be able to measure inhibin concentrations in blood and other biological fluids and thus determine the relationships between inhibin, spermatogenesis and the control of follicle stimulating hormone. If this goal is achieved it should increase our understanding or gonadal function not only in men but also in women.